Nakashima Kazunori, Maruyama Tatsuo, Kamiya Noriho, Goto Masahiro
Department of Applied Chemistry, Graduate School of Engineering, and Center for Future Chemistry, Kyushu University, 744 Moto-oka, Fukuoka, 819-0395, Japan.
Org Biomol Chem. 2006 Sep 21;4(18):3462-7. doi: 10.1039/b608920h. Epub 2006 Aug 7.
Subtilisin Carlsberg was covalently modified with comb-shaped poly(ethylene glycol) (PM13). PM13-modified subtilisin (PM13-Sub) was readily solubilized in three different ionic liquids (ILs), i.e., [Emim][Tf2N], [C2OC1mim][Tf2N] and [C2OHmim][Tf2N]. Analysis of homogeneous enzymatic reactions in the ILs revealed that PM13-Sub exhibited excellent catalytic performance while the native enzyme suspended in ILs showed no activity. Hydrophobicity of ILs slightly affected enzyme activity, and the relatively hydrophobic IL [Emim][Tf2N] was the preferred medium for enzymatic reactions, similar to enzymatic reactions in conventional organic solvents. Enzyme activity was much higher in [Emim][Tf2N] than in conventional organic solvents, and excellent activity was associated with unique properties of ILs such as hydrophobicity and high polarity. Furthermore, PM13-Sub showed good stability in [Emim][Tf2N], and maintained 80% of its initial activity after 60 h.
嗜热栖热菌蛋白酶（枯草杆菌蛋白酶卡尔伯格）用梳状聚乙二醇（PM13）进行了共价修饰。PM13修饰的嗜热栖热菌蛋白酶（PM13-Sub）能很容易地溶解在三种不同的离子液体（ILs）中，即1-乙基-3-甲基咪唑双（三氟甲磺酰）亚胺盐（[Emim][Tf2N]）、1-（2-乙氧基乙基）-3-甲基咪唑双（三氟甲磺酰）亚胺盐（[C2OC1mim][Tf2N]）和1-（2-羟乙基）-3-甲基咪唑双（三氟甲磺酰）亚胺盐（[C2OHmim][Tf2N]）。对离子液体中均相酶促反应的分析表明，PM13-Sub表现出优异的催化性能，而悬浮在离子液体中的天然酶则没有活性。离子液体的疏水性对酶活性有轻微影响，相对疏水的离子液体[Emim][Tf2N]是酶促反应的首选介质，这与传统有机溶剂中的酶促反应类似。在[Emim][Tf2N]中酶活性比在传统有机溶剂中高得多，并且优异的活性与离子液体的独特性质如疏水性和高极性有关。此外，PM13-Sub在[Emim][Tf2N]中表现出良好的稳定性，在60小时后仍保持其初始活性的80%。
